| 摘要 |
PURPOSE:To obtain the titled filter capable of producing in a low cost by lami nating the first thin film absorbing the infra-red ray having a prescribed wave length range and the second thin film composed of a material having a less refractive index than that of the first thin film on a glass substrate. CONSTITUTION:LWPF (Long Wavelength Pass Filter) is constituted by alterna tively laminating Ge thin films 2a-2d absorping the ray having <=1mum a wave length and the high refractive index, and SiO2 thin films 3a-3c having the less refractive index than that of Ge on the substrate composed of an optical glass. The LWPF is adhered the Ge thin film 2a having about 0.5mum the optical thickness of the film on the substrate 1, and then the SiO2 thin film 3a, the Ge thin film 2b, the SiO2 thin film 3b, the Ge thin film 2c and the SiO2 thin film 3c are laminated on the obtd. Ge thin film 2a in order, in about 1.0mum the optical thickness respectively, further, the Ge thin film 2d having about 0.5mum the optical thickness is laminated on the obtd. substrate, thereby hindering the infra-red ray having <=2mum the wavelength and transmitting the infra-red having >=2mum the wavelength.
|
